Presentation
Trauma with bilateral lower extremity flaccid paralysis
Patient Data
Images from a CT angiogram of the head and neck.
There is an acute fracture-dislocation at C7-T1 with grade 3 traumatic anterolisthesis of C7 over T1 and dislocation of the facet joints at that level bilaterally, compatible with locked facets. Anterior wedge fracture of T1 is noted with 15-20% loss of vertebral body height. A small avulsed bone fragment is also seen rising from anterosuperior corner of T1. There is associated moderate to severe narrowing of the central canal at C7-T1 with likely spinal cord compression.
Case Discussion
With facet dislocation, the inferior articular processes of the upper vertebra moves forward over the superior articular facets of the lower vertebra due to severe hyperflexion with distraction or shearing. This results in the naked facet sign (or Reverse hamburger bun sign) on the axial CT. Adjacent fractures of the vertebra can be seen.
Bilateral facet joint dislocation, "locked facets", is an unstable injury with high incidence of spinal cord injury and requiring urgent orthospine consultation for reduction and stabilization.
Case co-author: Rehana Jaffer, MD, FRCPC